1. Field of the Invention
The invention relates to a lampshade, particularly to a collapsible lampshade which has a flexible cover supported by a foldable frame.
2. Description of the Related Art
Lampshades are normally bulky and occupy large spaces during transport and storage. In order to reduce the spaces required by lampshades during transportation or storage, the prior art has suggested various forms of collapsible lampshades which can be kept in a compact size when collapsed. In one type of collapsible lampshade, separate multiple frame parts are provided for assembly into a lampshade frame, and a flexible lampshade cover is fitted over the lampshade frame. Since the frame parts and the lampshade cover are separated before assembly, they can be packed into a compact size to facilitate transport and storage. Another type of collapsible lampshade is produced by providing multiple complementary parts each having a frame part integral with a lampshade cover. The complementary parts can be stacked to reduce the lampshade size and can be interconnected to form a lampshade. Nevertheless, in either type of collapsible lampshade, there is a risk of loosing parts, or damage during shipment due to the movement of loose parts against one another.
In order to alleviate the aforesaid problems, U.S. Pat. No. 6,315,434 suggests a one-piece collapsible lampshade in which a frusto-conical flexible lampshade cover is integrated with a collapsible frame. The frame includes an upper ring attached to an upper end of the lampshade cover, a lower ring attached to a lower end of the lampshade cover, and a plurality support rods each having one end permanently and pivotally attached to the lower ring and another end removably inserted into a receptacle fixed to the upper ring. When the support rods are removed from the upper ring, both of the frame and cover are collapsed to a substantially flat configuration so that the lampshade can be kept in a compact size as a whole without separation. However, inconveniences are encountered when the support rods are to be attached to the upper ring to place the frame in an uncollapsed state because a considerable amount of energy is required to push or pull the upper ring away from the lower ring against the tension of the flexible cover so as to insert the support rods into the respective receptacles mounted on the upper ring. In addition, the force applied to the upper ring must keep the upper ring balanced in order to ensure extension of the support rods into the respective receptacles.
U.S. Pat. No. 5,375,048 discloses a collapsible frame which is comprised of upper and lower rings, and a plurality of rib members each having two ends respectively pivoted to the upper and lower rings. Each rib member has a hinge at its middle part and is thus foldable to permit the frame to lie flat with the upper and lower rings stacked. The frame additionally includes a slider disposed around each rib and slidable along the rib to move over and away from the hinge.
When each slider moves over the corresponding hinge, each rib is locked from its folding movement so that the frame can be stretched to an uncollapsed state. The frame further includes a spider disposed between the upper and lower rings to operate the sliders. This collapsible frame requires extra components to lock the frame in a stretched state and thus has a complicated construction.
An object of the present invention is to provide a collapsible lampshade with a simple construction in which foldable ribs can be unfolded and locked in a stretched operative state without the need to provide extra components.
Accordingly, a lampshade of the present invention comprises: an upper ring; a lower ring; a plurality of upper ribs each having a first end pivoted to the upper ring, and a second end part; a plurality of lower ribs each having a third end pivoted to the lower ring and a fourth end part, the fourth end part having a connection part pivoted to the second end part, the connection part having a pair of flaps extending over two opposite sides of the second end part and pivoted to the second end part; and releasable interengagement elements formed on the flaps and the second end part to engage the second end part with the flaps and to lock the second end part from movement relative to the flaps.